Diarrhea often develops as a side-effect disorder during the clinical treatment course by pharmacotherapy, whose typical symptom is characterized by the frequent defecation of liquid or liquid-like stools. In particular, the diarrhea due to the administration of cancer chemotherapeutics is often so serious that most patients with such a diarrhea symptom are no longer allowed to receive the further continuous treatment. Furthermore, this diarrhea endangers the patient's physical strength and nourishment, leading to slowing down the recovery pace from leukopenia, thrombocytopenia and the like, symptoms caused by administration of cancer chemotherapeutics.
There are already various chemotherapeutics widely used, for example, antimetabolites, such as 5-fluorouracil and derivatives thereof such as 5-fluorouracil, doxifluridine and tegafur, 5-fluorouridine, and methotrexate, compounds derived from plants, such as camptothecin, etoposide and vincristin sulfate, alkylating agents such as cyclophosphamide, anticancer antibiotics such as adriamycin and mitomycin C, cisplatin, and carboplatin, but these chemotherapeutics are known to commonly cause the foregoing diarrhea when used. In particular, this side effect is serious in the cases that its onset has been caused by, in particular, the continuous intravenous drip infusion of 5-fluorouracil or the administration of 5-fluorodeoxyuridine, doxifluridine, tegafur, cyclophosphamide, vincristine sulfate or irinotecan. So far, little is known about the detailed mechanism of diarrhea development. However, as far as cancer chemotherapeutics are concerned, it is speculated that diarrhea might be influenced pathologically by factors such as a direct affection to digestive tract mucosa, namely, chemical changes of mucosal cells, and further changes of enterobacterial flora. Yet there has been no established effective means for improving diarrheric symptom due to cancer chemotherapy, though effort is continued by some attempts such as alleviation of the diarrhea by changes in the usage and dose of cancer chemotherapeutics, improvement in their preparations, modification and conversion of compounds.
However, none of such attempts have seen sufficient improvement against the foregoing diarrhea symptoms as yet. Thus, there is growing demand for development of an agent for preventing and treating diarrhea, which has higher safety and stronger efficacy.
As described above, the present state is such that there are not yet any efficacious and safe agents for preventing and treating diarrhea, specifically a pharmaceutical agent for alleviating diarrhea due to cancer chemotherapy. It is therefore an object of the present invention to provide an excellent agent for preventing and treating diarrhea.
The present inventors have thus carried out an extensive investigation. As a result, it has been found that conagenin or a salt thereof is efficacious against various diarrheic symptoms, in particular, a diarrheic symptom due to cancer chemotherapy, thus leading to completion of the present invention.